球腔类航天器液体大幅晃动及刚液控耦合动力学研究

The spherical fuel containers are widely used in modern aerospace engineering due to their height volume to weight ratio. Firstly, the physical properties of the free surface tension and the motion mechanism of contact line in spherical cavity under microgravity environment will be studied and the reliable numerical algorithm about surface tension and contact line will be consequently completed. Then it is realizable to design a deft and effective mesh moving and update strategy suitable for large amplitude liquid sloshing in complex geometric containers. Subsequently, the computer numerical simulation with high precision will be carried out to predict three dimensional large-amplitude liquid sloshing in spherical tanks under microgravity environment. Based on that, the nonlinear phenomena for large amplitude liquid sloshing under various external excitations will be revealed and the bifurcation mechanism for resonance, rotation and chaos will be explored. Furthermore, the parameters of large amplitude liquid sloshing under microgravity environment will be extracted and the equivalent mechanical model for large amplitude liquid sloshing can be developed. The simultaneous equations of coupled rigid-liquid-control system will be built, as well as the investigations on the rigid-liquid-control coupling dynamics for liquid filled system will be conducted. Lastly, the emphases will be focused on the analysis of the stability and bifurcation and nonlinear control for the nonlinearly coupled system to design the adaptive control strategy for the orbit and attitude maneuver of liquid filled spacecraft. The innovative methods and theories including the modeling of dynamically coupled rigid-liquid-control system and the control strategy of the coupled liquid filled spacecraft system with large amplitude liquid sloshing, critical values for the key parameters, computational results and integrated computer simulation software for the coupled multi-body system.

由于球形燃料贮箱具有高容重比而使得其在现代航天工程中被广泛应用。本项目将对微重环境下球形腔内液体表面张力物理特性和接触线运动机理开展深入研究并完成其可靠的数值算法，设计适用于三维复杂几何形状贮箱中液体大幅晃动问题的网格更新策略，实现微重力液体大幅晃动高精度数值仿真。揭示各种激励下液体大幅非线性晃动现象并探讨其发生共振、旋转分岔及混沌现象发生机理。以仿真与分析和试验相结合的方法提取微重力环境下液体大幅晃动的动力学参数并发展完善液体大幅晃动等效力学模型；推导航天器刚-液-控耦合系统动力学方程并进行充液系统刚液控耦合动力学研究。开展对非线性耦合系统的稳定性、分岔及非线性控制方面的研究。设计充液航天器轨道及姿态机动自适应鲁邦控制器。重要研究成果包括球腔类充液航天器刚液控耦合系统的建模方法和理论、大幅晃动类充液航天器耦合系统非线性动力学与控制的理论和方法、临界参数值、数值仿真结果及计算机仿真软件。

本项目对微重环境下球形腔内液体表面张力物理特性和接触线运动机理开展了深入研究并完成其可靠的数值算法，设计适用于三维空间中复杂几何贮箱液体大幅晃动问题的网格更新策略，实现了微重力液体大幅晃动高精度数值仿真。.建立了航天器刚-液耦合系统数值仿真模型。通过液体受惯性力、刚体受流体作用力与力矩来实现系统的耦合，采用交错方法（staggered algorithm）对液体晃动模块与刚体动力学模块进行迭代求解。成功通过数值仿真观察到耦合系统中贮箱横向振动的非线性软弹簧特性、液体的高阶模态响应，分析了液体晃动对耦合系统的影响。进一步考虑了航天器控制系统，采用比例微分控制策略实现了航天器的大角度姿态机动与姿态稳定控制，并发现液体晃动对航天器的作用力与力矩存在复杂变化，其幅值并不总是大于不允许液体晃动的情况。.在刚-液耦合研究的基础上，进一步考虑柔性附件振动对航天器动力学的影响，将柔性附件简化为Euler-Bernoulli梁，建立了航天器刚-液-柔耦合系统数值仿真模型。采用交错方法对液体模块、主刚体模块、柔性附件模块进行多步迭代完成耦合系统的数值仿真。通过将仿真结果与文献中结果进行对比，证明了本文方法的有效性与准确性。然后研究了刚-液-柔耦合航天器在轨道驱动力作用下的响应，发现在算例工况下液体晃动与柔性附件振动互相影响，液体、主刚体与柔性附件之间存在着复杂的耦合效应。.重要研究成果包括球腔类充液航天器刚-液-控耦合系统的建模方法和理论、大幅晃动类充液航天器耦合系统非线性动力学与控制的理论和方法、临界参数值、数值仿真结果及计算机仿真软件。

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